Google-calendar – Remove past events from Google Calendar

You may want to take a look at Google's Calendar Sync:

Google Calendar Sync allows you to sync events between Google Calendar and Microsoft Outlook Calendar. You'll be able to determine the direction of information flow, as well as the sync frequency. Staying on top of your Google Calendar and Microsoft Outlook Calendar events has never been easier! Here's some good information to know to help you get started with Google Calendar Sync.

It lists as only being compatible with Outlook 2003 and 2007, so I'm not sure if it works with Outlook 2010.

There's an article on this here. I've not checked that it works, but it seems pretty straight forward. The essence is that instead of importing the calendar, you add the URL of your event feed as a public calendar - here's a summary of the steps:

1. In Facebook click on "Events"
2. Click on "Export Events" and copy the URL
3. In Google Calendar go to "Add" under "Other calendars" and choose "Add by URL"
4. Paste the URL you copied from Facebook and click "Add"

[Update: to make answer more complete]
If you run into issues with private events not showing properly then check out eventbusyfix.info. This site acts as an inbetween to clear the private flag and enable Gmail to show them properly (Thanks to prestomation for this tip)
[/Update]

Hope that helps!